Process of drawing yarns of polymers based on acrylonitrile in hot vapors of organic liquids



United States Patent 3,15%,223 6 F YARNS @lF PflJLYItliEl-ld @N ACRYLUNK'ERULE EN H691? @lZE-Ahiltl LEQUEPJ S En lie: id Stnchlih, Villeuriaanne, Marie ro er, We. issieuir, France, assignnrs to Cryler, i aris, France, a French body corporate No Drawing, Filed fillet. 27, likiil, No. 65,294- filaims priority, application France Nov. 3, 1959 Z illaims. (till. sea-ass;

This invention relates to the production of yarns and the like of polymers based on acrylonitrile and more particularly to a process for drawing (stretching) such yarns and the like.

By the expression polymers based on acrylonitrile used in this specification is meant polymers, copolyrners, grafted polymers and their mixtures containing from 85% to 100% of acrylonitrile and up to of one or more copolymerizable ethylenic compounds. By the term yards is meant an assembly of filaments obtained by dry or wet spinning, which assembly may be small in the case of continuous filaments and larger in the case of tows of high count intended to be cut or cracked to obtain discontinuous fibers.

It is known to effect the drawing of synthetic yarns in air by simple contact with a heating element or in various heated liquids or in steam. it is also known to effect the drawing of incompletely formed cellulose derivatives while they still consist of a soft interior and an external crust and before they have been freed from their solvent after softening of the external crust by solvent vapors.

It is an object of the present invention to provide an improved method for drawing yarns and the like consisting of polymers based on acrylonitrile which are free from contained solvent.

According to the present invention there is provided a process for the production of yarns and the like of polymers based on acrylonitrile (as hereinbefore defined) which comprises drawing such yarns or the like, while free from contained solvent, in a medium comprising the vapors of amyl alcohol, amyl acetate, and cyclohexanone.

1n the preferred form of the invention the vapors are maintained at a temperature close to, and usually slightly below, the boiling point of the liquid, so that the drawing is effected more conveniently in the vapors of the boiling liquid.

By the process just defined it is possible to draw the yarns or the like to a higher degree than has hitherto been practicable, the maximum drawing at which breakage of the yarn occurs being considerably higher than in the drawing processes hitherto known. Moreover, for a given degree of drawing, the tenacity is higher after drawing according to the invention than after drawing by the previously known methods. The process of the invention may be applied to the drawing of yarns obtained by dry spinning or by wet spinning.

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fiend, 2.2, E96 1- The following examples will serve to illustrate the invention:

Example I A polyacrylonitrile yarn is washed with water to eliminate the residual solvent. The limit to which this yarn may be drawn in boiling water or steam at C. is at most a drawing to 9X. When it is drawn in a hot zone containing cyclohexanone vapors at 153 (3., the limit to which the yarn may be drawn, i.e., at which breakage of the yarn occurs, is 16.5

Example II A yarn obtained by spinning a mixture of 85% by Weight of polyacrylonitrile and 15% by weight of polyvinyl acetate is freed from its solvent and then drawn in a zone containing amyl alcohol vapors at 131 C. It can be drawn to a degree of ll.4 Whereas the same yarn can be drawn in steam only to a degree of 9X.

Example 111 A polyacrylonitrile yarn freed from its solvent is drawn 7X in cyclohexanone vapor at 153 C. lit then has a dry tenacity 20% higher and an elongation 18% higher than the same yarn drawn to the same degree in steam.

Example .1 V

A tow of continuous copolymer filaments consisting of 92% by weight of acrylonitrile and 8% by weight of methyl methacrylate is freed from its residual solvent and then drawn in saturated amyl acetate vapor at C. It can thus be drawn Without difliculty to an extent 34% higher without breakage than is possible when the yarn is drawn in steam.

We claim:

1. A process for the production of yarns of polymers based on acrylonitrile which comprises drawing such yarns, While free from contained solvent, in a hot medium comprising the vapors of an organic liquid selected from the class consisting of amyl alcohol, amyl acetate and cyclohexanone.

2. A process for the production of yarns of polymers based on acrylonitrile which comprises drawing such yarns, while free from contained solvent, in a hot medium comprising the vapors of an organic liquid selected from the class consisting of amyl alcohol, amyl acetate and cyclohexanone, the said vapors being maintained at a temperature substantially that of the boiling point of the liquid of which they are the vapors.

References Cited in the file of this patent Ul'll JED STATES PATENTS 2,476,069 Snyder July 12, 1949 2,499,477 Feild Mar. 7, 1950 2,768,057 Priederich Oct. 23, 1956 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pa tent No $150,223 September 22, l 1964 Rene Emile Fernand Stuchlik et a1 It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below In the grant (only) line 1 for Rene Emile Fernand Sturchlik" read Rene Emile Fernand Stuchlik Signed and sealed this 2nd day of March 1965,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Altesting Officer Commissioner of Patents 

1. A PROCESS FOR THE PRODUCTION OF YARNS OF POLYMERS BASED ON ACRYLONITRILE WHICH COMPRISES DRAWING SUCH YARNS, WHILE FREE FROM CONTAINED SOLVENT, IN A HOT MEDIUM COMPRISING THE VAPORS OF AN ORGANIC LIQUID SELECTED FROM THE CLASS CONSISTING OF AMYL ALCOHOL, AMYL ACETATE AND CYCLOHEXANONE. 